Let U be the set of all triangles in a ...

NCERT Class XI Mathematics - Sets - Solutions

Question : 48 of 73

Marks: +1, -0

Let U be the set of all triangles in a plane. If A is the set of all triangles with at least one angle different from 60°, what is A′?

Solution:

Here U = {x : x is a triangle}

A = {x : x is a triangle and has at least one angle different from 60°}

∴ A′ = U – A = {x : x is a triangle} – {x : x is a triangle and has atleast one angle different from 60°}

= {x : x is a triangle and has all angles equal to 60°}

= Set of all equilateral triangles.

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